arXiv subjects

Hamza Ouarrad

Publications and source records attributed to Hamza Ouarrad.

4 recordsLinked to original sources

arXiv2026

LLM Ensemble Fault Classification for Automotive HiL Validation

Automotive HiL validation generates large multivariate test recordings whose analysis remains challenging due to manual review effort, rule-based limitations, and the need for explainable diagnostic decisions. Recent machine-learning and deep-learning approaches have improved fault diagnosis, but they often require large labelled datasets, generalise poorly across operating conditions, and provide limited insight into their predictions. This paper proposes an explainable multi-LLM ensemble framework for sensor-level fault classification in automotive validation. The framework uses compact evidence representations of fault-injection recordings and combines the outputs of heterogeneous large language models to improve diagnostic robustness, ranking quality, confidence reliability, and interpretability. The approach is evaluated on gasoline-engine and electric-vehicle HiL systems across three driving settings and ten single-fault classes. Among the individual models, Mistral Small~24B provides the strongest overall single-model trade-off, achieving 0.903 Top-1 accuracy, 0.887 MCC, and the lowest Brier score of 0.102. The final Top-3 ensemble combines Mistral Small~24B, Qwen2.5~32B, and Phi-4~14B using confidence-weighted voting, improving the scenario-averaged results to 0.917 Top-1 accuracy, 0.913 macro F1, and 0.902 MCC, while also providing the best calibration among the tested ensemble strategies. A Top-5 ensemble does not improve over the Top-3 configuration, indicating that model complementarity is more important than ensemble size. The results show that coordinated multi-LLM reasoning can support robust, calibrated, and engineer-interpretable fault classification for automotive HiL validation.

cs.SE↗

arXiv2026

Knowledge-Graph-Guided Retrieval-Augmented LLMs for Explainable Root Cause Analysis in Automotive HiL Validation

Hardware-in-the-Loop validation of automotive software systems generates large multivariate time-series recordings whose manual analysis is time-consuming and often limited to anomaly detection and fault classification rather than root-cause analysis. Although deep learning methods have shown strong performance in fault detection and classification, they usually require task-specific training or retraining when new fault locations, systems, or operating conditions are introduced. They also tend to treat localization as a classification task, without explicitly representing the spatial and functional relationships between fault locations, sensors, and downstream subsystem effects. This limits their generalizability and their usefulness for engineering root cause analysis and diagnosis. This paper proposes a knowledge-graph-guided retrieval-augmented large language model framework for RCA (root cause analysis) and fault localization in automotive HiL data. The method converts raw time-series recordings into compact diagnostic evidence, enriches this evidence with sensor-to-location and propagation knowledge, and retrieves similar historical cases to support the final reasoning step. The LLM is then used as a decision and explanation layer rather than as a direct time-series classifier, producing a ranked fault-location prediction together with an interpretable RCA explanation. The framework is evaluated on two automotive HiL case studies: an ASM gasoline engine and an electric vehicle system. The best-performing model achieves Top-1 accuracies of 90\% and 94\%, respectively, while recording-level aggregation reaches perfect file-level fault localization in the evaluated subset. These results demonstrate the potential of KG-guided RAG-LLM reasoning for explainable and generalizable HiL RCA.

cs.CR↗

arXiv2026

Sensor-Level Fault Diagnosis for Automotive Software Validation Using Large Language Models

The pre-series validation of automotive software on hardware-in-the-loop (HIL) platforms produces large volumes of multivariate sensor recordings whose assessment against functional safety requirements exceeds what manual review can sustain at campaign scale. Threshold-based tooling reports that a deviation has occurred but neither identifies its nature nor locates its source, while data-driven classifiers, although accurate, rely on large labelled datasets and return opaque decisions that sit uneasily with the traceability demanded by ISO 26262. This study examines whether open-source instruction-tuned large language models (LLMs), given a textual description of sensor behaviour, can serve as data-efficient and interpretable engines for fault detection and diagnosis inside the validation loop. A two-phase framework is proposed: automated requirement checking on a dSPACE real-time platform first isolates the recordings that violate a safety requirement, and only these are inspected, with sliding windows of the signals reduced to statistical, relational, and contextual descriptors, embedded in a fixed prompt, and mapped by a 4-bit low-rank-adapted LLM to a fault location accompanied by a written justification. Four model families ranging from two to eight billion parameters were adapted and tested on a gasoline-engine case study spanning six injected fault classes. The smallest model matched the largest at 81.6\% accuracy, whereas a comparably sized model failed to converge, indicating that diagnostic competence under task-specific adaptation follows convergence rather than parameter count, with the entire adapt-and-evaluate cycle fitting on a single commodity accelerator.

cs.SE↗

arXiv2026

Fault Detection and Explainable Classification in Automotive HIL Validation via Denoising Autoencoders and In-Context Large Language Models

Validating automotive software systems produces large multivariate test recordings that are still examined through effort-intensive manual review and rule-based evaluation, which detects faults beyond predefined rules poorly. Machine and deep learning have advanced fault diagnosis, yet most supervised models require large labelled datasets, generalise poorly to unseen conditions, and offer little insight into their decisions. We propose a generalisable and explainable two-phase framework for fault detection and classification during real-time validation. A denoising autoencoder trained only on healthy signals first flags abnormal behaviour through reconstruction-error analysis, removing the need for fault labels. Each abnormal window is then encoded as compact textual statistical evidence relative to a time-aligned healthy reference and classified by a frozen large language model under zero-shot and few-shot prompting, returning the predicted class, ranked alternatives, a confidence value, the fault location, and a short evidence-based explanation. Eight open-source models are evaluated across two powertrains and three driving regimes. The detector attains average F1-scores of 0.97 across powertrains and 0.98 across regimes, with average mean error below 0.03. Zero-shot prompting proves insufficient (best 0.519 F1-score), whereas few-shot prompting reaches perfect discrimination under stable regimes, showing that prompting strategy, rather than parameter count, governs classification quality: a nine-billion-parameter model surpasses every zero-shot medium and large model. Mistral Small 24B is adopted as the main pipeline model for its balance of accuracy, class-balanced reliability, calibration, and inference cost, giving engineers interpretable diagnostic reports and more efficient validation.

cs.SE↗